Aware



. June 7, 1927.

H. F. WEISS WALL BOARD AND PROCESS OF MAKING THE SAME Filed Aug. :22.1921 R v Q Q0 w lNlE/YTO Howard Fit B Patented june 7, 1927.

UNITED STATES PATENT OFFICE.

HOWARD I. WEISS, OI MADISON, WISCONSIN, ASSIGNOR, BY MESNEgASSIGNHENTB,TO WOOD CONVERSION COMPANY, OF CLOQ'UE'I, MINNESOTA, A CORPORATION OFDEL- AWARE.

WALL BOARD AND rnocnss or MAKING THE sum.

Application flee August 22, 1921. semi No. 494,150.

There are now on'the market three general pes of wall board made fromwood. "The st type is made as follows: Round wood is ground into amechanical pulp on "grinding equipment such as is used in makingordinary ground wood pulp for. paper manufacture. To this ground woodpulp is added a certain amount of chemical pul to give added strength tothe finished pro uct,

then the mixture is flowed over an ordinary board machine into a sheetof paper having the thickness of ordinary card-board.

At the end of the paper ma ing machine the sheets are wound into rollsof a size convenient for transportation. The wall board is made fromthem by un-rolling five rolls or more simultaneously and gluing orcementing the various sheets of paper together, usually with an adhesivesuch as sodium silicate. The sheets of paper or card-board thus gluedtogether are then out to the desired size and dried and in this form arecommercial wall board. Some manufacturers use waste pa ers in whole orin part instead of groun round wood, but without change'in theessentials of the process as above outlined. Wall boards of this typeare sold in the United States in greater tonnage than those of any othertype.

A second type of wall board now on the market is made by grinding thewood to a pulp and then beating the pulp in standard paper makin heatersand finally flowing it into trays; t ese trays are then put into ahydraulic press and the mass is compressed into a dense product which isthen removed from the press, dried, trimmed, and surfaced. Chemical pulpcan be substituted in whole or in part for ground wood pulp in this typeof oard. 'This board consists of but one layer, and usually is denserand has a more compact surface than wall board made from paper sheets.

A third type of wall board is made by gluing or cementing between twoheavy sheets of paper, slats of wood placed side by side. This board isexpensive because of the cost of the wood slats and because of therelatively large quantity of sodium silicate or other adhesive that mustbe used in holding the slats together and in fasteningthe coveringsheets firmly to the wood.- The covering sheets are relatively tough andthick and have the characteristic appearance and surface texture ofpaper.

These three types include all of the various varieties of wood wallboard now on the market in a large way. They all involve the of goodsize and qualit which, if not used in the manufacture 0 wall board,could 'well be used in the manufacture of newsprint paper and even moreexpensive papers,

aside from the standard pulp-making equipment used in these processes,the boards themselves are made on large and expensive machines requiringlarge floor area; the single exception being the one dply board made ona press as above outline All of the wall boards above described relymainly for their strength upon the interlacing and interlocking o thefibers and, there fore, their rocesses of manufacture aim to make a pu phavin fibers as long as possible. In general, or best results, thisrequires the use of round wood of good quality and of grinding equipmentwell designed and carefully maintained. But. around everysaw mill thereaccumulates large quantities of what may be termed saw mill offal orwood waste, such as slabs, edgings, trimmings, sawdust, shavings, andbark. Some of this material such as the slabs and edgings, ismarketable, under favorable shipping conditions, to "aper mills, butthough the quality of fiber 1n the slabs and edgings is as good orbetter than the general run of fiber from round wood, the pieces of woodare in such physical condition that they are not readily reduced to apulp,v with the result that the yield of fiber is low, the quality ofthe pulp is poor, and the practical difilculties of operation areenormous.

Also. around every saw mill there accumulates large quantities of decaed wood. Some of this is usually saw mill offal or wood waste such asslabs, edgings and trimmings for which there has been no market and,continued exposure of which to the elements has resulted in decay of thewood. Some of the rotted wood is usually from the hearts of overripetrees or from lumber piles not properly protected. In general, therotting or decay of wood is the result of the action of fungi whichattack the lignin components of the wood by a process of oxidationwhereby the lignin is largely converted into a gas and so passes offinto the atmosphere. The usual fungi do not attack the celluloseconstituent of the wood and do not attack the resin components to anyappreciable extent.

There is .a small market for decayed boards, not for building purposes,but as a facing for the surface of the ground when ore is to be piledup; but in accordance with my present invention, such inferior lumbercan be put to better use and I can even use wood that has so far decayedas to have substantially no mechanical strength. For instance, I canmake use of the hearts of logs that are so far oxidized by the fungithat the wood falls apart and has to be swept up with a broom. Suchmaterial is not as good for my purpose as sound wood, but there are someadvantages resulting from its relatively high cellulose content and itsrelatively high resin content. The power consumption necessary forputting this rotted Wood into proper-condition for use in accordancewith the present invention is of course relatively low because of thephysical weakness of the material.

Any wall board process that depends for its raw material ongrinding'round wood on a stone requires the expenditure of largequantities of power. For example, a ton of ground wood pulp, suitablefor making the plies of a wall board, requires 1200 to 2400 orsepowerhours for grinding alone. This great quantity of power is consumed,partly in the mechanical work of tearing the fibers one from another,but more largely in frictional loss at the surface of the stone where itrubs with heavy pressure on the log of wood andwhere the log acts as abrake on the stone. This frictional loss is dissipated in the form ofheat and the heat is carried away in the cooling water and thus is lost.The cooling water, after separation of the fibers, is ordinarily run towaste.

It is an object of the present invention to provide a ready market forsaw mill offal or wood waste, including decayed wood.

It is a further object of the present invention to produce a wall boardconsisting essentially of a single ply. this board prefer- .ably beingfree from sodium silicate and being uniform throughout. The board mayhave a surface that is dense and capable of taking a good finish andeven a high polish, and if desired can be ornamented by graining andpainting *uethods now well developed in the decoration of sheet materialsuch, for instance, as sheet metal.

It is a further object of the present invention to produce a wall boardof acceptable character from saw mill offal such as slabs, trimmings,edgings, sawdust, shavings and even bark and decayed wood, and to dothis with .a power consumption far below that ordinarily needed and inmachinery and buildings less expensive than those now needed for theproduction of wall board from ground Wood or from chemical pulp. Otherobjects and advantages of the present invention will become clear fromthe following description which is to be taken in conjunction with theaccompanying drawings, wherein:

Figure 1 is a diagrammatic representation,

in elevation, of a complete plant for making wall board by the presentprocess, and Fig. 2 is a diagrammatic plan view of the same.

The wall board of the present invention comprises a binder and a fillerand the novelty in the product lies particularly in the binder and inits combination with a filler of special character. There is alsonovelty in the process of making and using the binder, particularly forthe manufacture of a wall board such as that hereinafter described.

The binder consists essentially of lignocellulose gelatinized bymechanical disintegration preferably in the presence of water andpreferably with the aid of a gelatinizing chemical such as caustic soda.This binder per se when dried is a hard and horny mass having goodbinding qualities and yet offering no impediments to usual wood workingoperations such as sawing, planing, chiseling. and the like. The bindercan be 'made from sawdust or somewhat larger particles of raw wood andpreferably is made bycrushing or rolling thewood particles betweenrelatively rotating discs whereby the fibers are torn apart andsubjected'to pres-' sure in the presence of water and ultimately areconverted in part at least into a gelatinized mass. If wood particlesother than sawdust are used as the raw material for the binder. they arepreferably obtained by chipping, hogging or shredding mill waste oroffal or decayed wood, and not. by grinding solid wood on a stone as inpulp making.- As

a step in the gelatinization or partial gelatinization "of the sawdustor similar wood particles. a water-logging procedure is applied to theparticles to facilitate their mechanical disintegration and conversioninto gelatinous material. Preferably this waterlogging operation isapplied to the wood after it has been reduced to a fineness cons parableto that of sawdust, or even finer than this.

The filler need not be separate fibers, as

excellent results are had by using bundles of fibers such as sawdustpreferably screened to take out the finest and the coarsest particles.Incompletely gelatinized wood par- T he binder.

Starting with saw mill offal or waste, such as slabs, edgings,trimmings, shavings, and

barker, I pass the waste through a hog such as is used at saw mills forcnttin up waste wood to make it suitable for fue or through a chipper,such as is\ used in preparing wood for the soda, sulfite or sulfateprocess, or through a coarse shredder; such as is sometimes used at sawmills in place of a hog to reduce wood to small chips or fragments. Ifdesired, a hog and a shredder may be used .in conjunction, the hogcutting the wood into fragments say two inches long, and the shredderbeating these fragments into smaller pieces. Good sound round wood canof course be used as raw material but mill waste is much cheaper and isentirely satisfactory. All of these operations which, for lack of abetter name, I will hereinafter designate as chipping, are carried outby a cutting action which requires very much less power than if thewaste were reduced to a pulp by holding solid blocks of it against arapidly rotating stone as in grinding wood for ground wood pulp. Also,the product resulting from chipping is entirely different from groundwood, pulp.

Thus. by chipping, the saw mill or paper mill ofi'al is reduced to amass of chips or wood particles of a size aboutone-half inch in lengthby one-eighth inch in diameter, or less. If the mill waste is all in theform of sawdust, or other like small particles, the

chipping and shredding steps can be omitted.

These small wood particles (which. as above explained, may benothingmore than sawdust or may be larger particles), are

' next passed into hopper 2 (Fig. 1) preparatory to delivery into amachine 3' whereby they are torn apart and reduced in part, butpreferably not' entirely to separate fibers. The machine 8 forseparating'the fibers may be constructed in many ways but best resultshave been obtained by me in an apparatus having two discs of metal, oneof which is rotatable with respect to the other and between which thesawdust orother relatively small wood particles are subjected to arolling action to tear, or more strictl speaking crush the fibers onefrom anot ier. Goot results have been obtained by the use of discgrinders commonly known as corn crackers of which the 36 single discmill of Bauer Bros. Company, Springfield, Ohio, U. S. A., is a goodillustration. Thedetails of such a disc grinder or'corn cracker are wellillustrated in U. S. Patents Nos. 565,696"

and 817,610. In such a machine the action of tearing the wood fibersapart resembles somewhat the disintegrating effect of rolling a woodenmatch under foot on the floor, excepting, however, that because of therelative rotative movement of the discs, each piece of wood or bundle offibers has a gyroscopic motion about the axis of the rotating disc sothat not onlyare the fibers and bundles of fibers subjected to acrushing action, but they are subjected to a twisting effect. As onedisc rotates with respect to the other, the small wood particles orbundles of fibers will naturally take up positions along radii of therotating disc and.- since their outer ends travel through a greaterdistance than their-inner ends, there will be a decided tendency for thefibers to slip longitudinally with a twisting movement. That is to say,there is not only a crushin g pressure perpendicular to the axes of theindividual fibers, but there is a strain,

-in shear, superimposed on the crushing strain and parallel to the axesof the fibers, or more strictly speaking, radial to the rotating plateof the machine; It will be understood that the two plates of themachinebetween which the particles are rolled have slightly concavedfaces andcan be roughened or surfaced toaccelerate the disintegrating action orfiber liberation. Both plates may rotate in opposite directions, or

grinding action that gives best results in the manufacture of theproducts hereinafter described. Too much of the grinding for tearing thefibers apart on an ordinary paper mill grindstone; for not only has thechipping and shredding cut the fibers from the solid wood, but thedisintegrating or fiber liberating power has been applied to theparticles in compression and in shear, and therefore along their linesof least resistance. Also, in this process, friction and 'frictionallosses have been reduced to a minimum. The bundles of fibers act asrollers between the moving surfaces while rolling one upon the other. Nowater need be added at this stage.

To reduce the wood to the desired condition, it may be passed repeatedlythrough the same fiber liberating machine. Or, if desired, a series offiber liberating machines may be used in each succeeding one of whichthe relatively moving surfaces are so adjusted as to give bestdisintegrating action on the partially reduced wood with which it issupplied. The latter procedure is pref-- erable and passage throughthree of the grinders will disintegrate the sawdust or similar woodparticles to the extent desired at this stage of the process.

A suitable arrangement of the three grinders is indicateddiagrammatically in Fig. 2 of the drawing. where the material deliveredfrom disc grinder 3 to box 4 is carried by an elevator 5 to a hopper 6adapted to deliver to a disc grinder 7. \Vhen delivered from the latterto box 8, the mass can be lifted by either of conveyors 9 or 10 anddelivered to the hopper of grinders 11 or 12, which in turn deliver totank 13 from which the mass ultimately can be conveyed to other discgrinders of the series.

The next step consists in conveying the finely divided wood from storagetank 13 to a tank 14 where a water-logging procedure :is initiated. Thiswater-logging -is used because wood that is wet is very much weaker andcan be torn apart with less expenditure of energy than wood that isdrythe fibers separate from one another more easily. For xample, wetwood has, in compression, about one-half to one-third of the strength ofdry wood; Thiswater-logging can he done conveniently by first submergingthe fiber aggregates in water heated nearly or preferably to the boilingpoint, and then, while the wood particles are submerged in a closedtank, subjecting the mass to pressure, such as steam pressure, to forcethe hot water into the fiber aggregates.

As an alternative procedure, the fiber aggregates can be thoroughly.heated in the traction of the expanded air and gases, as

above described. Under some circumstances it is more economical merelyto let the hot water and the submerged wood particles cool by radiation,for by so doing. large quantities of water will be drawn into the poresand voids of the wood.

By such a treatment fiber aggregates (such as sawdust or chips that havebeen mechanically disintegrated in the three grinders) can be sothoroughly saturated with water that they will sink in water in an houror less. If they were merely submerged in water, it would take monthsand, in the case of resistant woods, years. before the fiber aggregatessoaked up enough wa- 3 ter to sink. The heating in hot water is notintended to be a cooking operation and there need be no chemical presentto effect cooking. Nevertheless, the hot water dissolves out some orperhaps all of the highly soluble constituents of the wood. lVhenwestern larch is used as the wood, this is a. valuable feature of theprocess because'of the possibility of recovering valuable sugar makingingredients from the liquor.

As an alternative and the preferred procedure, the water is hot andcontains 1% of caustic soda (NaOH) by weight. and the fiber aggregatesare soaked in this liquor at boiling temperature and at atmosphericpressure for about one hour. after which the fiber aggregates are dumpedinto a second tank containing caustic soda solution of the same strengthbut at room temperature. These operations can be carried out in tanks 14and 15 where 14 is the hot soda tank and 15 is the cold soda tank. Thepresence of soda facilitates the penetration of moisture into the fiberaggregates and in addition is a component useful in subsequent steps ofthe process.

From tank 15 the cold and water-logged fiber aggro ates, together withthe soda liqnor, are de ivered to a. press 16 for the removal andrecovery of the caustic soda liq.- uor. This recovered liquor isreturned to one of the soda tanks and is used over again. This press maybe of the roller type such as was commonly used for squeezing the liquorfrom malt sprouts in the beer industry. This moist mass of water-loggedfiber aggregates, impregnated with a small quantity of caustic soda. isnext delivered to a hopper 17, and from there passes into a secondserics of grinders similar in structure to those above described, butwith their platescloser feet may not be very great in grmder 18together. The soda content will then be about 40 lbs. per ton of fiberag regates,

gregates. This water can besupplied con-- veniently, by means of a pipe19 which delivers a steady stream into the top of hopper 17. The use ofwater in the mill is to acilitate the flow or flushing out of thematerial and not because of the cooling action of the water. In fact hotwater can best be used for this purpose, because of its effect inlowering the resistance of the wood to the crushing action and similardisintegrating stresses. No caustic soda or other chemical need be addedto the water for the fiber aggregates have already been charged withenough of the caustic soda to insure the results desired.

The ulpy mass delivered by grinder 18 is lifted by a pump 20 to a secondgrinder 21 where the disinte rating treatment is repeated. Ordinarilytime of these grinders are sufficient to produce the effect desired,though more than that number can be used when more complete chemical andphysical changes of the wood are deemed advisable.

As the wood proceeds through this series of grinders the particles orfiber aggregates are torn apart to yield separated individual fibersand, furthermore, these fibers undergo a chemical change and ultimatelyare delivered from the last grinder of the series into storage tank 22in a gelatinous structureless form well adapted for use as a binder inthe wall board of m resent invention. But with the individua ers soseparated and gelatinized, there is mixed a relatively high percentageof fiber aggregates that have resisted complete physical disintegrationand are gelatinized only on the surface.

It is well recognized in the literature that the hydration qualities oflignocellulose or wood are not very great and that mechanical wood pulpsuflers little alteration by beating in a paper maker s beater. But Ihave found that when lignocellulose or wood is crushed or rolled underpressure in a corn cracker and in the presence of water, h dration willbegin even with the first mill of the series and the hydration willrogressively increase as the wood is re need to fiber and the fibers arebroken and crumbled under pressure. The water-loggingtreatment to whichthe wood has been subjected and the addition to it of a small quantityof caustic soda both facilitate hydration. However, it is entirelypossible to produce a elatinized liguocellulose without giving it t ewater-logging treatment and by merely rolling and breaking the fibers incold water.

by dry weight, Caustic potash can e used'as a.

out, crush, and gelatinize the fiber While the hydration or gelatinizingef- (Fig. 2), the other and particularl the last grinders of the seriesin which t e plates are set close together, so completely comb gregatesthat the'fibrous structure of a arge proportion of the separated fibersdisappears entirely. I

As above explained, the resultant product is a slimy mass oflignocellulose consisting in part of gelatinized fibers and in part ofundisintegrated and superficially elatinized fiber. aggregates. Thegalatinize lignocellulose might perhaps be called hydratedlignocellulose, though I know of no method for determining how manywater molecules have attached themselves to the cellulose molecule, orif indeed any such water molecules have been added. I know that thechemical structure of the gelatinized material must be different fromthat of lignocellulose, and as appears below, the physical structure islikewise radically different. Therefore, for lack of a better name, Ihave herein designated this material, which. is to be the binder orbinding element of the wall board, as gelatinized lignocellulose.Gelatinized lignocellulose, as the term is herein used, means woodfibers (lignocellulose) that have been so treated mechanically as to becompletely torn and broken so that their len th is but a fractional partof their original ength, say, for instance,- one-tenth or less;,furthermore, the original wood cellulose has been changed chemically andperhaps to the extent of adding to it an un known number of watermolecules. The gelatinous com onent of the material delivered from theast grinder, when wet, is a slimy mass which on drying. shrinksenormously and is inclined to warp and forms a dense, hard, bone-likemassof considerable strength and without appreciable fibrous structure,but inclined to split or flake and of a color usually somewhat darkerthan that 'of the wood from which it was made. Made from pine, spruce orhemlock the material is cream colored, and made from fir, tamarack orlarch it is somewhat darker in color. It can be made readily from any ofthese woods and others, but with cedar the rob lem is more difiicultbecause of diflicult es in chemically changing the water-reslstantfibers of such gymnosperms.

Both physically and chemically, gelatinized lignocellulose is readilydistinguishable from wood flour,.though according to my experiments,wood flour often results from prolonged mechanical treatment of woodfiber, as, for instance, when the fiber is passed repeatedly through aJordan. The ulpy mass of partially elatinized lignocel ulose deliveredby the ast grinder of this series 'is the material used by me for ansthe production of wall board in accordance with the present invention.The gelatinized component of this lignocellulose mass not onlyconstitutes an appreciable percentage of the total material used, butacts as a binder to unite with and hold in place the other and moreinert material or materials with which it is associated. These othermaterials properly may be designated as the filler.

A. feature which readily may be incorporated in the above describedprocess of making gelatinized lignocellulose is the recirculation of thewater in some, at least, of the fiber-liberating machines which, withthe soluble material in the wood, can be recovered in a manner similarto that described in my- U. S. Patent No. 1,339,489, issued May 11,1920. Furthermore, whenever a plurality of fiber-liberating machines areused in series to progressively reduce the wood particles to pulp, andthen to gelatinize the pulp, the circulation of the water to take outsoluble material (as from western larch), can be on the counter-currentprinciple, that is to say, the water used in the last machine or grinderof the series can be filtered ofi from the pulpy material deliveredtherefrom and can be introduced as the flushing water of the machinenext preceding, and so on throughout the series, the strongest solutionof soluble constituents being drawn ofl from the partially disintegratedshredded wood particles of the machine into which these particlesinitially were delivered.

When the pulpy mass is delivered from the last grinder it consists, asabove explained, of gelatinous lignocellulose, adapted to serve as thebinder of the wall board, and other material somewhat like sawdust butmore finely divided, and with the component particles gelatinized on thesurface. I have called these small wood particles fiber aggregates andby fiber aggregates I mean five or more wood fibers still 'oinedtogether as in the living tree. The bers need not, however, be of fulllength and ordinarily are not.

The relative proportions of the two ingredients of the mixture may bevaried throu h relatively wide limits. Up to a certaln point the largerthepercentage of gelatinized lignocellulose the stronger s the resultantboard. The board should contain 25% or more by dry wood weight of thegelatinized lignocellulose and 30% or more by dry wood weight of fiberaggregates. Amixture composed of 60% gelatinized lignocellulose and 40%fiber aggregates by dry wood weight to which enough water has been addedto makethe mass flow readily gives a very strong, stifi and satisfactorywall board. pr'uce or pine give a stronger board than cedar but any oneof these woods or mixtures of. any of them are suitable.

The sizing.

While the pulpy mass is being mechanically disintegrated in grinders 18,21 and succeeding grinders, there preferably is added to it a solutionof sodium resinate in water, and after this has been thoroughly mixedwith the mass and ground into it, a water solution of alum is introduced(as at the last grinder) to convert the soluble sodium resinate into aninsoluble resinate. This treatment sizes the fiber. aggregates, and alsosizes the gelatinized lignocellulose, and makes them and the finishedboard highly resistant to moisture. The sizing is uniform throughout theentire board. These sizing materials may be omitted entirely whenwaterproofing is not desired without injuring the' strength or othercharacteristics of. the board, excepting that of its resistance towater. Normally the percentage of sodium resinate may be from two toeight per cent of the dry weights of the other components, depending onthe amount of wood used and particularly its resinous content and thedegree of waterproofing desired in the finished product. When decayedwood is bein used in appreciable quantity, this wood, i of a coniferousvariety, may be abnormally high in its percentage of resin, and underthese con-- ditions due allowance must be made in the percentage ofresinate added to the pulp. The quantity of alum is in proportion to thesodium resinate, due allowance being made for the amount of waterpresent etc.

If a fireproof board is desired. the requisite amount of ammoniumsulfate or analogous fire retardant can be added to the batch anduniformly ground into it while it is assing through this series ofgrinders.

non-mineral coloring, such as an aniline dye, can also be added if acolored board is desired. This is particularly advantageous when theboard is to be finished in imitation of mahogany.

Pressing.

The now thoroughly mixed mass of sized gelatinized lignoce lulose andwood fiber aggregates is next delivered to a flow box 23 (Fig. 2) likethose in ordinary paper making machines, and so constructed as tomaintain a constant head in the box with an overflow through pipe 24into the underground storage tank 22 (Fig. 1). A constant stream of thepulpy mass flows out of a horizontal slot in the side of the box under agate 25. This gate is provided with a rack and pinion 26 by which it mabe raised or lowered to vary the size 0 the stream. As the thick mixture'flows through the slot it is delivered in a uniformly thick layer on atraveling wire screen or conveyor 27 which is mounted on. cylinders 28and onto the w1re conveyor is approximately the length of layer.

The width .of the wire screen conveyor or belt corresponds with thelength of the board or panel to be made, and the cellulosic mass isprevented from flowing ofi the sides of the conveyor by means of twostationary baffles 31 (Fig. 2). These baflles are adjustable laterallytoaccommodate several widths of cellulosic mass to accord with changesin "the boards to be made. In eneral, a board length of 16 feet issuitable or ordinary trade demands. Converging boards 32 smooth off thetop of the pulp Thus the cellulosic mass in a relatively thick anduniform layer 16 feet wide and 2 inches thick on the wire screenconveyor is carried forward between the stationary baflles 31 andultimately passes between the platens of a powerful press. wire screenconveyor moves forward with an intermittent movement and as soon as theproper amount of the mass is between the platens a rectangular die 33,having inside dimensions corresponding to the size of the board to bemade, is'lowered into the mass until it rests on the wire screenconveyor. The cellulosic mass is so fluid that it readily moves aside topermit this lowerin of the die. Then the upperlaten, which ts within thedie with a su stantially water-tight joint, is lowered into the dieandcompresses the cellulosic mass, while simultaneously squeezing itsexcess water both upward and downward through suitable slots in theplatens. It is advantageous to appl suction to these openings in the topan bottom platens to facilitate prompt removal of the water. Much of thewater drips out of the mass while it is on the wire screen and before itreaches the press, but the proportion remaining should be reduced bypressure and suction to about of the total weight of the compressedboard. A pressure of 200 lbs. per square inch applied aduall over aperiod of half a minute and sit on or a period of five to ten secondswill, when su plemented by adequate suction, efiect t a desiredextraction. The liquor thus drawn from the pulpy mass is not thrown awabut, on the contrary, is fed back into t e last series of grinders,thereby economizing in water and conserving whatever binding agents andother soluble'eomponents of value mayhave passed into the water. As soonas the compressing is completed. the suction is cut off and air underpressure is applied in place of the suc- Th removes tion. The platensthen separate, the compressed air releases the board from the platens,the die lifts, and'the wire screen conveyor moves forward rmtil a freshamount of material has passed between the platens when the operationjust "described is repeated. This operation is done mechanically andtakes less time than a minute to press each sheet.

Drying.

of a damp, fairly stiff, compressed sheet.

Suction plate 34'is adjustable vertically in supports 35 totransfer thecompressed sheet vertically and sidewise into a dry kiln 36. This kilnmay be of the tunnel type heated by steam coils and provided with wellknown means for regulating'the circulation of air, its humidity,temperature, etc., to secure most effective and uniform drying action,and to lessen such tendenc as there may be for warp-age of the boar s.The dry kiln the water from the boards so that they emerge from the kilndry, hard.

Finis hing.

The boards are next run through saws and stiff and a cut to desired sizeor shape and in that form,

are marketable in place of wall board made by usual processes. Theboards may be nailed directly to the studdin of a building to serve inplace of lath and p aster, and like wall board now on the market, may besawed and similarly cut to meet the needs of the builder. But unlikewall boards of more usual manufacture, the contain no sodium silicate orother minera harmful to the saws and other edge tools of the carpenter.On the contrary, they consist throughout of nothing but woody materialthrough which a saw or chisel will work as readily as through solidwoodand with no more injury to the edge of the tool. The resin size and theammonium sulfate, if present, are not harmful to edge tools.

Such small amount of caustic soda as remains with the cellulosicmaterial after squeezing of the mass at press 16 is neutralized by thealum and gives to the product no objectionable characteristics.

In many respects this new roduct is different from wall board m e frompaper sheets cemented together, for, if desired, the wall board of thepresent invention may be passed through an ordinary wood planer tofinishthe surface, or through a sand machine to dress its surface, or betweensteel rolls to give the surface either a high polish or to' impress inor on the surface patterns or designs or to give a finish similar toburlap -it the appearance of grained mahogany or other woods. Thesurface can be painted and decorated much as can be done with solidwood, excepting that it has not the characteristic grain of wood, but onthe contrary, if made with fiber aggregates, has a uniform and pleasingmottled appearance not unlike the so-called oatmeal wall papers.

As above indicated, the process by which 'this novel and valuableproduct is made,

may vary in many of its details, both as to the origin ofthe rawmaterials and as to the procedure by which these materials are treatedto bring them into proper physical and chemical condition to unite underpressure and kiln drying into the product described in detail above. Itis of particular importance, however, that no chemical need be used inthe process and that water alone, together with suitable mechanicalmanipulations, such as cutting, rolling, and twisting, properlyrepeated, is suflicient to convert saw mill offal such as slabs,edgings, trimmings, sawdust, shavings and even ba-rk, into a readilymarketable product and with relatively low power consumption.

Theap aratus whereby the process is carried out o viously may vary indetails without fundamentally altering either the process or the productclaimed herein. Novel features of the apparatus will be claimed in a.separate application. The present application describes furtherdevelopments in the invention described and claimed in my copendingapplication, Serial No. 470,967, filed May 19, 1921.

I claim 1. The method of preparing a wall board binder, which consistsin chipping saw mill oflal, crushing and rolling the chips until reducedto small particles and then waterlogging said particles, andmechanically disintegrating the water-logged particles while wet untilat least 25% of themass by dry wood weight has been reduced to astructureless, gelatinous mass, substantially as described.

2. The method of preparing a wall board binder, which consists inchipping saw mill ofl'al, repeatedly crushing and rolling the chipsuntil reduced to small particles, then water-logging sa'id particles,and repeatedly crushing and rolling the water-logged.par ticles betweenrelativelyrotating discs, substantially as described.

-- 3. The method of preparing gelatinous;

lignocellulose, which consists in chippingsaw mill ofl'al, repeatedlycrushing and rolling the chips while dry until reduced to smallparticles, water-logging said particles, and then repeatedly crushingand rolling said water-logged particles between relatively r0- tatingdiscs until'converted into gelatinous lign'ocellulose to the extentdesired, substantially as described.

4:. The method of preparing a wall board binder, which compriseschipping saw mill oflal, reducing the chips to small Wood particles byrepeatedly crushing and rolling the chips while dry, water-logging saidsmall particles and mechanically disintegrating the water-loggedparticles in water until at least 25% of the fibers have been crushedand broken and converted into a structureless gelatinous mass.

5. The method of making wall board, which consists in mechanicallydisintegrating small wood particles to form a mass consisting of about50% gelatinous lignocellulose and 50% of fiber aggregates by dry wood,weight, shaping and pressing into a board and drying and finishing theboard, substantially as described.

6. The method of making Wall board, which consists in water-loggingsmall wood particles, crushing and rolling said particles while wetuntil converted into gelatinous ligno-cellulose to the extent of morethan 25% and less than by dry wood weight, shaping and pressing into aboard and drying and finishing the board, substantially as described.

7. The method of making wall board, which consists in reducing saw milloflal to small particles, water-logging said particles by heating inwater and then cooling, then mechanically disintegrating said.waterlogged particles until converted into gelatinous ligno-cellulose tothe extent of more than 25% and less than 70% by dry wood weight,flowing the mixture into a layer, pressing said layer into a board anddrying and finishing the board, substantially as described.

8. The method of making wall board, which consists in chipping saw millofl'al, repeatedly crushing and rolling the chips until reduced to smallparticles, water-loggin-g said particles, then mechanicallydisintegrating said particles in water uutil'converted into gelatinousligno-cellulose to the extent of more than 25% and less than 70% by drywood weight, flowing the mixture into a layer, pressing said layer intoa board and drying and finishing the board, substan-. tially asdescribed.

9. The method of making wall board, which consists in reducing saw millofl'al to small particles, water-logging said particles, repeatedlycrushing and rolling said waterlogged particles while wet untilconverted into gelatinous ligno-cellulose to the extent of more than 25%and less than 70% by dr wood weight, sizing the mixture during saidconversion, flowing the mixture into a layer, pressing said layer into aboard and drying and finishing the board, substantially as described. I

10. The method of making wall board, which consists in reducing saw millofial to small particles, water-logging said particles by heating inwater and then cooling, repeatedly crushing and rolling said waterloggedparticles until converted into gelatinous ligno-cellulose to the extentof more than 25% and less than by dry wood weight, flowing the mixtureinto a layer, compressing said layer into a board, and drying andfinishing the board, substantially as described.

11. The method of making wall board, which consists in/reducing saw milloffal to small particles, water-logging said particles by heating inwater containing caustic soda and then cooling, pressing to remove andrecover the alkaline liquor, then repeatedly crushing and rolling saidwater-logged particles in water until converted into gelatinousligno-cellulose to the extent of more than 25% and less than 70% by drywood weight, flowing the mixture into a layer, compressing said layerinto a board, and drying and finishing the board, substantially asdescribed.

12. The method of making wall board, which consists in reducing saw milloflt'al to small particles, water-logging said particles by heating inwater containing about 1% of caustic soda and then cooling, pressing toremove and recover the alkaline liquor, then repeatedly crushing androllin said water-logged particles in water unti converted intogelatinous ligno-cellulose to the extent of more than 25% and less than70% by dry wood weight, flowing the mixture into a layer, compressing.the layer into a board with simultaneous sucking of moisture therefrom,and drying and finishing the board, substantially as described.

13. The method of making wall board, which consists in reducing saw millofi'al to small particles, water-logging said particles by boiling themabout an hour at atmospheric pressure in water containing about 1% ofcaustic soda and then cooling, pressing to remove and recover thealkaline liquor, then repeatedly crushing and rolling said water-loggedparticles in water until converted into gelatinous ligno-cellulose tothe extent of more than 25% and less than 70% by dry wood weight,sizing. and fireproofing the mixture during said conversion, flowing themixture into a layer, compressing said layer into a board withsimultaneous sucking of moisture therefrom, and drying and finishing theboard, substantially as described. Y

14. The method of making wall board, which consists in chipping saw millofi'al, repeatedl crushing and rolling the chips while ry until reducedto small particles, water-logging said particles, repeatedly crushingand rolling said water-logged particles in water between relativelyrotating discs until converted into gelatinous lignocellulose to theextent of more than 25% and less than 70% by dry wood weight, flowingthe mixture into a layer, compressing said layer into a board, anddrying and finishing the board, substantially as described.

15. The method of making wall board, which consists in chipping saw milloffal, repeatedly crushing and rolling the chips while dry betweenrelatively rotating discs until reduced to small particles,water-logging said particles by heating to about boiling temperature inwater containing an alkali and then cooling, pressing to. remove andrecover the alkaline liquor, then repeatedly crushing and rolling saidwater-logged particles in water until converted into gelatinousligno-cellulose to the extent of more than 25% and less than 70% by drywood weight, flowing the mixture into a layer, compressing said layerinto a board, and drying and finishing the board, substantially asdescribed.

16. The method of making wall board, which consists in chipping saw millofi'al, repeatedly crushing and rolling the chips while dry untilreduced to small particles, water-logging said particles by heating inwater containing caustic soda and then cooling, pressing to remove andrecover the alkaline liquor, then repeatedly crushing and rolling saidwater-loggedparticlesin water until converted into gelatinouslignocellulose to the extent of more than 25% and less than 70% by drywood weight, flowing the mixture into a layer, pressing said layer intoa board, and drying and finishing the board, substantially as described.

17. The method of making wall board, which consists in chipping saw millofl'al, repeatedly crushing and rolling the chips while dry untilreduced to small particles, waterlogging said particles by heating inwater containing about 1% of caustic soda and then cooling, pressing toremove and recover the alkaline liquor, then repeatedly crushing androlling said water-logged particles in water until converted intogelatinous lignocellulose to the extent of more than 25% and less than70% by dry wood weight, flowing the mixture into a la er, pressin saidlayer into a board, and rying and ishing the board, substantially asdescribed.

18. The method of making wall board, which consists in chipping saw milloffal, repeatedly. crushin and rolling the chips while dry until reducedto small particles, water-logging said particles by heating in watercontaining about 1% of caustic soda and then cooling, pressing to removeand recover the alkaline liquor, then repeatedly crushing and rollingsaid water-logged particles in water until converted into gelatinouslignocellulose to the extent of more than 25% and than 70% by dry woodweight, sizing and fireproofing the mixture repeatedly? crushing androlling the chipswhile dry until reduced to small particles,water-logging said particles by boiling them about an hour atatmospheric pressure in water containing about 1% of caustic soda andthen cooling, pressing to remove and recover the alkaline liquor,' thenrepeatedly crushing and rolling said waterlogged particles in wateruntil converted into gelatinous lignocellulose to the extent of morethan 25% and-less than 70% by dry wood weight, sizing and fireproofingthe mixture during said conversion, flowing the mixture into a layer,vcompressing said layer into a board, with simultaneous sucking ofmoisture therefrom, and drying and finishing the board, substantially asdescribed. I

20. Artificial lumber consisting essentially of a dried gelatinous massof mechanicall disintegrated lignocellulose intermixed wit fibergelatinized on the surface.

21. Artificial lumber consisting essentially of a dried gelatinous massof mechanicall disintegrated li ocellulose intermixed wit fibergelatinize on the surface, a dried gelatinous mass constituting 25% to70% of the lumber by dry wood weight.

22. Artificial lumber consisting essentially "of a dried gelatinousmassof mechanically disintegrated lignocellulose intermixed withfibergelatinized on the surface, the, dried gelatinous mass comprisingabout 40% of the lumber by dry wood weight.

' 23. Artificial lumber comprising a dried gelatinous mass ofmechanically disintegrated lignocellulose'intermixed with fiberaggregates gelatinized onthe surface.

24. Artificial lumber comprising a dried gelatinous mass of mechanicallydisintegrated lignocellulose intermixed with fiber aggregatesgelatinized on the surface, the,

fiber aggregates constituting about 50% 0f the lumber by dry woodwelght.

25. Artificial lumber consisting essentially of a dried gelatinous massof mechanicall disintegratedlignocellulose intermixed wit '55 I theresidue of mechanically disintegrated and partially gelatinized fiberaggregates.

26. Artificlal lumber comprising a dried gelatinous mass of mechanicallydisintegrated lignocellulose intermixed with a resi due of partiallygelatinized fiber aggregates,

said mass'being waterproofed throughout.

-27. Artificial lumber comprising a dried gelatinous unass ofmechanically disintegrated lignocellulose intermixed with a rest-- 5 dueof partially gelatinized fiber aggregates, said mass being fireproofeduniformly. throughout.

28. Artificial lumber consisting essentially of a dried gelatinous massof mechanically 7 disintegrated lignocellulose intermixed with while wetto form a mass of about 50% ge-r latinous lignocellulose and 50% offiber ag- 80 gregates by dry wood weight, shapin and pressing into aboard and drying and nishing the board, substantially as described.

30. The'method of making wall board which consists in mechanicallydisintegrat- 85.

ing small'wood particles until converted into gelatinous lignocelluloseto the extent of more than 25% and less than by dry wood weight, shapingand pressing intoa making wall board board and dryin and finishing theboard at substantially as escribed. v In testimony whereof I aflix mysignature.

:HOWARD F. wnrss. f

